Currently, a delay circuit generally provides a delay time depending on a charging time of a capacitor in the delay circuit. In order to adjust the delay time of the delay circuit, parameters of resistor-capacitor (RC) components in the delay circuit have to be adjusted, such that the charging time of the capacitor can be adjusted. As the charging time of the capacitor depends on a capacitance of the capacitor and a charging current, a capacitor with a large capacitance is needed when the charging current is small. In this case, circuit losses and costs are increased, which is unfavorable for circuit design.
Additionally, the capacitance of the capacitor and the charging current may deviate from their respective expected values because of being susceptible to an external circuit, which results in that the delay time of the delay circuit has a low accuracy.